The objectives and methods are: To determine structural and functional roles of lipids in Leishmania species, by determining their qualitative and quantitative distribution in various organelles (kinetoplast-mitochondrion, pellicle, endoplasmic reticulum, nucleus, flagellum), of promastigotes in culture in chemically-defined media under various environmental conditions, and of amastigotes in the vertebrate host. Chromatographic and spectrometric analyses will be used to correlate lipid composition and metabolism of leishmanias with their ability to cause cutaneous, mucocutaneous, or systemic infections.